Genie Engine (Age of Empires) .DRS file reader/writer in Node.js
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README.md

genie-drs

Genie Engine DRS file reader/writer for Node.js and the browser

.DRS files are archive files used in the Age of Empires 1 and 2 and Star Wars: Galactic Battlegrounds games. A format specification is available in the openage project.

NPM

Usage Example

Read a palette file and a unit graphic from the Age of Empires 2 data files:

var DRS = require('genie-drs')
var Palette = require('jascpal')
var SLP = require('genie-slp')
var PNG = require('pngjs').PNG

// using Age of Empires 2 files
var int = DRS('interfac.drs')
  , gra = DRS('graphics.drs')

// id 50500 is the main in-game palette.
int.readFile(50500, function (err, buffer) {
  if (err) throw err
  var palette = Palette(buffer)
  int.close()
  onpalette(palette)
})

function onpalette (palette) {
  // 3088 is the 'Champion Dying' graphic.
  gra.readFile(3088, function (err, buffer) {
    if (err) throw err
    var slp = SLP(buffer)
    onslp(palette, slp)
  })
}

function onslp (palette, slp) {
  var frame = slp.renderFrame(1, palette, { player: 1, drawOutline: false })
  var png = new PNG({
    width: frame.width,
    height: frame.height
  })
  png.data = Buffer.from(frame.data.buffer)
  png.pack().pipe(fs.createWriteStream('champion-dying.png'))
}

Create a new DRS file:

var DRS = require('genie-drs')
var after = require('after')
var drs = DRS()

var cb = after(3, onfinish)
fs.createReadStream('./somefile.slp').pipe(drs.createWriteStream('slp ', 1, cb))
fs.createReadStream('./bgm.wav').pipe(drs.createWriteStream('wav ', 2, cb))
fs.createReadStream('./palette.pal').pipe(drs.createWriteStream('bina', 3, cb))

function onfinish () {
  drs.archive().pipe(fs.createWriteStream('./archive.drs'))
}

API

DRS([options])

Create a new DRS file. Options can be:

  • isSWGB - Whether this is a file for Star Wars: Galactic Battlegrounds. Default false.
  • copyright - Copyright string to use, uses the Age of Empires or Star Wars: Galactic Battlegrounds string by default. This should be exactly 40 characters long for DRS files intended for AoE and exactly 60 characters long for DRS files for SWGB.
  • fileVersion - Version number as a 4-character string, default '1.00'.
  • fileType - File type as a 12-character string, pad with NUL bytes. Default 'tribe\0\0\0\0\0\0\0' like in Age of Empires 2 files.

DRS(filename: string)

Node only!

Creates a new DRS instance for the .DRS file filename.

DRS(blob: Blob)

Browser only!

Creates a new DRS instance for the given Blob instance.

DRS#read(callback)

Reads the DRS table headers. This only needs to be called manually if getFiles() or getSize() is used. Otherwise, genie-drs will call it automatically when necessary.

DRS#getSize(): number

Returns the size of the DRS file. Includes any unsaved modifications. Won't work if the file hasn't been .read() yet.

DRS#getFiles(): Array<{id, type, size, offset}>

Returns an array of all the file entries in this DRS file. Format:

{ id: Number     // internal file ID
, type: String   // 4-character, space-padded type of file: "wav ", "slp ", "bina"
, size: Number   // file size in bytes
, offset: Number // file offset in the main DRS, in bytes
}

Won't work if the file hasn't been .read() yet.

DRS#getFile(id: number): { id, type, size, offset }

Finds one file entry by its file ID. See DRS#getFiles()

DRS#putFile(type: string, id: number, buffer: Buffer, callback)

Replaces one file in the DRS.

type is the file type, i.e. the table in which to store the file. If a file type is given for which a table does not exist, a new table is created. id is the new file ID. buffer is a Buffer or string with the new file contents.

DRS#readFile(id: number[, options], callback)

Reads a file's contents for ID id. The callback gets an err and a Buffer containing the file contents.

Optionally, provide an options object to read only part of the file:

  • start - Byte offset inside the file to start reading at.
  • end - Byte offset inside the file to stop reading at.

DRS#createReadStream(id: number[, options]): Readable

Returns a Readable stream of the file contents for file ID id.

The returned stream also emits a meta event with information about the file, like in getFiles().

Optionally, provide an options object to read only part of the file:

  • start - Byte offset inside the file to start reading at.
  • end - Byte offset inside the file to stop reading at.

DRS#createWriteStream(type: string, id: number): Writable

Returns a stream, stuff that is written to it will be saved in the DRS file. Note that this method works in-memory, use the archive() method to flush changes back to disk.

The returned stream emits a meta event with information about the new file, like in getFiles().

type is the file type, i.e. the table in which to store the file. If a file type is given for which a table does not exist, a new table is created. id is the new file ID.

DRS#archive(): Readable

Returns the entire DRS file as a stream. If the DRS instance was initialized from an existing DRS file, this method may attempt to read data from that file--it's not safe to pipe the stream straight back to the original DRS file. If that is necessary, use a module like fs-write-stream-atomic, which will not touch the initial file until everything has been read.

var createWriteStream = require('fs-write-stream-atomic')

var drs = DRS('./archive.drs')
fs.createReadStream('./custom-palette.pal')
  .pipe(drs.createWriteStream('bina', 50501))
  .on('finish', onfinish)

function onfinish () {
  drs.archive().pipe(createWriteStream('./archive.drs'))
}

License

MIT